This invention relates to a projectile release mechanism for facilitating launching of a jet-propelled projectile, particularly a spherical spin-stabilized missile, and for insuring proper alignment of the missile with its spin axis during initial separation.
It has become increasingly important to eliminate the features associated with a ballistic trajectory ordinarily followed by rockets and other jet-propelled projectiles, by forming the projectiles as spherical spin-stabilized missiles. The spherical missile spins about an axis upwardly inclined relative to the intended straight line path of flight and aligned with the thrust axis of the propulsion jet of the missile. The missile is released following ignition or activation of the jet propellant within the missile. The propulsion is effected by the reaction of the exhaust jet of, for example, a rocket motor housed within the spherical missile shell.
Often such spherical spin-stabilized missiles are provided in conjunction with attachments secured to the front end of an assault weapon such as a rifle.
Such spin-stabilized spherical jet-propelled missiles experience difficulties in remaining stabilized during attainment of desired rotational speed and in coordinating the spinning and release of the missile. Release of the missile prior to attainment of adequate rotational speed can result in unstable flight. Delay of release after attainment of adequate rotational speed can result in a loss of propulsive range.
Consequently, attempts have been made to provide means for temporarily restraining and automatically releasing a spin-stabilized jet-propelled spherical missile during spinup. For instance, in U.S. Pat. No. 3,245,350 to J. A. Kelly, dated Apr. 12, 1966, a mechanical release is provided between a rifle barrel and a spin-stabilized spherical missile in order to selectively release the missile. However, precise automatic release is not afforded. More specifically, U.S. Pat. No. 3,554,078 to Joseph S. Horvath, dated Jan. 12, 1971, provides a fusible link for temporarily restraining and automatically releasing a spherical spin-stabilized missile during spinup. Release of the spherical rocket missile from its rotary supporting means is effected by causing hot missile rocket exhaust gas to weaken by heating or to heat and soften or melt a separate fusible link member which, prior to weakening by softening or melting, secures the missile to the rotary support means. In this patent, the separate fusible link member is of the nature of a brazing alloy serving as one part of a nozzle assembly to secure the rocket to the rotary support means. The fusible link member is brazed between two separate fore and aft nozzle portions which are permanently secured to the missile and to the support means, respectively, as by threaded engagements.
In copending application Ser. No. 206,370, filed Nov. 13, 1980, to Alan Clark Baker and Joe Thomas Zinn, Jr., entitled "Release Apparatus For Jet-Propelled Projectiles," and assigned to the assignee of the present invention, a new and improved nozzle assembly is disclosed. The nozzle assembly includes a unitary nozzle member having fusible joint means formed integrally therewith, between the missile and the rotary support means, thereby eliminating the assembly and brazing operations of prior devices as shown in the Horvath patent, and thereby considerably reducing manufacturing costs and improving accuracy. However, in this application the fore and aft sections of the unitary nozzle, forwardly and rearwardly of the fusible joint means, are permanently fixed to the missile and to the support means, respectively, as by threaded engagements.
The present invention is directed to providing a further new and improved nozzle assembly in which the projectile support means includes open-ended receptacle means out of which the fore and aft sections of the nozzle can move on fusing and separation of the fusible joint means. The invention also includes novel means for accommodating thermal expansion of the nozzle member, particularly at the fusible joint means.